Microphones are generally classified into a non-directional (whole directions) microphone and a directional microphone according to directional characteristics. Such directional microphones are classified into a bi-directional microphone and a uni-directional microphone. The bi-directional microphone exhibits faithful reproduction characteristics for front and rear incident sounds, but exhibits reduction characteristics for a lateral incident sound. Thus, a polar pattern of the bi-directional microphone for a sound source describes a figure eight. Also, the bi-directional microphone has favorable near field characteristics, which is widely used for announcers in noisy stadiums. The uni-directional microphone maintains an output value in response to a wide front incident sound, but reduces an output value of a rear incident sound source, to improve a S/N ratio for a front sound source, which has a good articulation to be widely applied to voice-recognition equipment.
While the directional microphones obtain directional characteristics by respectively forming sound holes in a case and a PCB surface and using a phase difference between a front sound and a rear sound through a single microphone, variable directional microphones, having variable directional characteristics through two non-directional microphones, have been developed.
In manufacturing a variable directional microphone assembly with two non-directional microphones, according to a related art, two non-directional microphone devices and a semiconductor integrated circuit device are directly mounted to a rigid printed circuit board (commonly referred to as a ??PCB??), so that mechanical configuration for supplementing sound characteristics are unsatisfactory. Thus, sound quality is poor, and miniaturization is difficult.